Hearing protectors are being used in environments where noise levels are high. Typically, hearing protectors comprise two ear cups and a device for fastening the hearing protector to the head of a wearer, so that the ear cups are positioned over the wearer's ears. Further, ear cups may be provided with active elements, such that the passive sound-reducing function is combined with the function of actively reproducing sound inside the ear cup to allow the user to hear this reproduced sound. Such an active elements typically include an electronic unit comprising a speaker.
The active element may incorporate different functions. One type of active element may, for instance, contain a radio receiver and the electronic circuitry required to reproduce the sound received by the radio receiver through the speaker. Another type of active element may be designed such that it is capable of reproducing ambient sound from the vicinity of the hearing protector. In this case, the hearing protector is typically provided with a microphone connected to the electronic unit. Another type of active element may enable communication with external devises connected to the hearing protector via electronic wire and/or wireless as via Bluetooth.
Electronic units provided with a speaker and a microphone have the function of receiving the sound from the microphone and converting it in such a manner that it is emitted by the speaker in the innercup at a level that conforms with relevant safety standards and is suitable for the wearer. Further, the electronic circuitry of the electronic unit typically comprises circuits for dampening frequencies and/or sound level that are particularly disturbing to the human ear for the benefit of the frequency range within which ordinary speech is situated. By such an arrangement, the wearer of an active hearing protector is able to talk to another person in a noisy environment without having to remove the hearing protector and without risking any hearing damage.
Evidently, the reproduced ambient sound will differ from the actually ambient sound, since some frequencies are being damped. Further, the reproduction of sound via a microphone-speaker arrangement will not be ideal. Thus, various measurements have been taken in the art to provide a good reproduction of ambient sound in ear cups provided with active sound reproducing arrangements.
WO 2008/100197 discloses an ear cup for a hearing protector, wherein the ear cup has noise-reducing space and at least one electronic unit with at least one speaker. Further, the ear cup has resonance space arranged to function as a sounding board for sound emitted by the speaker. By providing a closed resonance space the speaker is stated to provide a better bass sound.
WO 2006/118514 discloses an ear cup for a hearing protection unit which comprises an inner cup portion, which defines a noise damping space facing towards the user. The ear cup further has an outer cup portion for accommodating electronics and/or an electrical current source. The inner cup portion and the outer cup portion are separated by a partition which is of one-piece manufacture with the inner cup portion. The partition is substantially closed, with the exception of an opening in which a fixing portion on a bracket is disposed. The fixing portion is included/integrated with conductors to a loudspeaker. The bracket also has a baffle plate which extends along the periphery of the loudspeaker. The baffle plate is stated to improve the sound reproduction in lower frequency ranges. In this context, it is important to notice that the baffle plate does not, on its-rear side, screen off or possibly more or less seal off a volume that could reduce the size of the effective noise damping space. Although, the baffle plate is stated to improve the sound reproduction the provided solution, it is a space requiring solution. Further, the baffle may be uncomfortable for people having outstanding ears.
WO 2009/139682 discloses a hearing protector having two closed muffs which sealingly abut against the wearer's head, so that there is formed a closed space in each muff and about the user's ear. A loudspeaker is disposed interiorly in the muff and has a membrane whose one side is turned to face towards the user's ear, and whose opposing side is turned to face towards a closed volume which is defined by the membrane and an enclosure. In order to improve the base reproduction in listening to music, the interior of the enclosure is, via at least one hole or one duct, in flow communication with the ambient surroundings outside of the closed space of the muff. Although, the base reproduction is improved, the presence of a hole or a duct will imply that ambient noise may “leak” into the noise damping space.